It is 1 in 9x10^6 (1 in 9,000,000) because no-one's local phone number begins with zero. Zeroes are reserved for signalling the exchange that you are making a special type of call; eg emergency (000), out-of-area (0n nnn nnnn), mobile/cell (0nnn nnn nnn), etc.

1/(7x10^N).1 represents your phone number,7 represents the number of digits of your phone number, 10 represents the numbers that can be dial in a telephone and the N represents that how many times do you dial before you could possibly dial your phone number.....